The present invention relates to a communication system, and particularly to a communication system for establishing, maintaining, and managing a network.
Recently, there is an increasing demand for a short distance radio communication network. As an example of a low cost and low power consuming short distance wireless communication standard which realizes the short distance wireless communication network (also simply referred to as a network, hereinafter), ZigBee (registered trademark) has been devised (see Non-patent Document 1; IEEE Std. 802.15.4-2003, IEEE Standard for Information Technology).
Generally, in order to couple a plurality of nodes in a network when establishing a network, it is necessary to search for the nodes because it is required to constantly keep track of the location of all the nodes.
In order to search for the nodes, broadcast communication (multicast communication) is performed, for which various types of methods have been proposed (see Patent Document 1 (Japanese Patent Laid-Open No. 2000-134235) and Patent Document 2 (Japanese Patent Laid-Open No. 2000-353143)).